Alternating-current-motor starter.



W. H. GAULKE. ALTERNATING CURRENT MOTOR STARTER.

APPLICATION FILED 00w. 19, 1910.

1,009,661. Patented N0vl21, 1911.

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19mm Q COLUMBIA PLANDGRAPH 470., WASHINGTON, n. :4

UNITED STATES PATENT OFFICE.

WILLIAM H. GAULKE, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO INDEPENDENT ELEC- TRIC MANUFACTURING COMPANY, A CORPORATION OF WISCONSIN.

ALTERNATING-CURRENT-MOTOR STARTER.

To all whom it may concern:

Be it known that I, WILLIAM H. GAULKE, of Milwaukee, lVisconsin, have invented an Alternating-Current-Motor Starter, of which the following is a specification.

This invention relates to rheostats or resistance-boxes for electric-circuits and more particularly for that type which are known as starting-boxes which are used for starting and controlling electric motors. Such devices are provided with a quantity of resistance which is divided into sections by taps leading to contact-pieces on the face of the box, over which moves a pivoted contactarm which is connected with one pole of the circuit, and said arm is provided with a spring acting to bring it back when released to the starting-point, while an electromagnet energized by the line supplying current to the motor acts upon the armature carried by said pivoted arm to hold the latter in on position when it has been turned up to the last point, in which all the resistance is cut out of the crcuit. Hheretofore particular difficulty has been experienced with such boxes when used on alternate-current circuits because ofthe difficulty of producing a magnet which will invariably hold the contact-arm against the spring while the current is on, and yet invariably release it the moment the current is turned off. I have found that unless the magnet-coil is made quite strong, it is apt to release at times when the current is still on, while on the other hand, if made strong enough to hold reliably, it is inclined to be unreliable in the other direction, z'. 6., when the current is turned off suflicient residual magnetism is left in the magnet to continue the hold until broken. Other disadvantages of using a strong magnet are that it uses too much current and has too much inductance.

It is therefore the object of my invention to produce a holding-device for the contactarm especially adapted to alternate-current circuits; which will invariably hold the contact-arm when the current is on and invariably release it the moment the current is turned ofl, while at the same time using but very little current in the magnet. To this end I provide a special form of holdinglever or catch, at one end of which is mounted a special form of armature working in Specification of Letters Patent. Patented N 21, 1911, Application filed October 19, 1910.

Serial No. 587,823.

the arinautre and core, but also for exactly the right magnetic flux in the armature. Furthermore, in the most improved form of my invention, I provide an adjustable stop whereby the holding position of the armature with respect to the magnet may be varied, thereby correspondingly regulating the flux in the armature to correspond with the current or voltage of the circuit on which the device is used and to adjust against variations in the tension of the spring of the contact-arm.

My invention further consists in the constructions and combinations hereinafter described and specifically set forth in my claims.

My invention is illustrated in its most improved form in the accompanying drawings, wherein Figure 1 is a front-elevation of a rheostat constructed according to my invention, the magnet being shown in axial section; and Fig. 2 is a side-elevation of the same, the back of the rheostat being broken away, and the magnet being removed and its position shown by dotted lines.

The front-plate of the rheostat, on which is mounted the combination of parts constituting my invention, is designated a, and is secured to the rheostat-case by the usual screws 5, and may be provided with terminal-posts c. The contact-arm (Z is mounted to turn upon the post 6, provided with a handle f at its free end and making slidingcontact with a series of contact-plates g to which are connected the ends of the rheostatcoils in the usual manner, the contact-arm (Z is resiliently actuated to turn into the dotted-line position by a spring it, one end of which thrusts against a screw 2', and an abutment-post j is provided to limit the movement of the arm when in its off position. At the opposite end of its move ment, the travel of the handle 03 is limited by a post k, said post forming the pivot of the catch-lever Z, on whose lower end is mounted an armature m. Said armature cooperates with the iron core at of the magnetcoil 0, and this core as shown is hollowed out for a part of its length to a diameter somewhat larger than that of the armature m, whereby the armature m can enter the end of the core, but without touching the latter. A stop is provide to limit the movement of the armature m into the core, and this is preferably made in the form of a screw 2) threaded into the lever Z and provided with a jam-nut g for clamping it in its adjusted position.

To the upper end of the lever Z there is attached a bent bar or finger r, the end of this finger being bent obliquely to the motion of the contact-arm as shown at 8, being adapted to engage a pin 25 on the contactarm. It will be noted from the drawing that the contacting-surfaces are oblique, whereby the pin 25 produces a reaction upon the finger 1' tending to turn it and the contact-lever Z into the dottedline position. So long as current is flowing through the magnet-coil 0, the magnetic flux produced thereby will be sufiicient to hold the lever Z in the fullline position against the reaction at the point .9, and inasmuch as the armature m is much farther from the fulcrum of the lever than the point 8, a very weak magnetic flux can be made to serve the purpose, no matter how strong may be the spring h. The moment, however, the current ceases to flow, the magnet will cease to retain its armature, and in this case the tension of the spring it will move the handle toward the left and by throwing up the bar 0, the pin t will be released and the contact-arm be restored to the off position. This cannot fail to take place on account of residual magnetism, because since there is no contact between the armature and magnet-core there will be no residual magnetism.

While it is not essential to the invention, I prefer to make the bar 1 of resilient material and to mount it in a resilient manner as shown, the lower end being secured to the lever Z by a screw it, while the upper end is merely guided by the screw 0; without closely confining it, whereby the upper end of the bar has a certain amount of free motion due to its resiliency. For the sake of convenience in handling, it will also be desirable to so combine the elements that the bar Z requires no manipulation to engage it with the arm (Z when the latter is turned into the on position. To this end it will be noted, first, that the movement of the bar Z is limited by the lower end thereof striking againstv the base of the contact-arm at w; and secondly, that the end 5 of the finger r is guided into place first by the point 2? striking its oblique end-surface :v, and secondly by the base of the handle f striking its upper surface. This latter action turns the lever into the full-line position by the time the handle (Z strikes against the pin is, and when in this position it is retained there by the magnet.

I wish it understood that my invention is not limited to the use of all the above described features and constructions, for some may be omitted and others may be varied or modified in various ways, as will readily occur to those skilled in the art.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a device of the class described, means for holding a contact arm, comprising an electromagnet having a magnetic core which is bored out internally for a part of the distance from one end thereof, and an armature operatively connected with said contact-arm and mounted to move in a path coaxial with said core and to enter the end thereof a greater or less distance.

2. In a device of the class described, means for holding a contact arm, comprising an electromagnet having a core which is bored out internally for a part of the distance from one end thereof, an armature operatively connected with said contact-arm and mounted to move in a path coaxial with said core and to enter the end thereof a greater or less distance, and an adjustable stop adapted to limit to a variable extent the movement of said armature toward said core.

3. In a device of the class described, means for holding a contact-arm comprising an electromagnet having a core which is bored out internally for a part of the distance from one end thereof, and an armature operatively connected with said arm and mounted to move coaxially with said core and having a diameter substantially smaller than the bore thereof.

4:. In a device of the class described, means for holding a contact-arm comprising an electromagnet having a core which is bored out internally for a part of the distance from one end thereof, an armature operatively connected with said arm and mounted to move coaxially with said core and having a diameter somewhat smaller than the bore thereof, and an adjustable stop adapted to vary the limiting position of said armature in moving toward said core.

5. In a device of the class described, in combination with a movable catch-device, an armature mounted thereon, said catch device having movement independent of the armature, a magnet adapted to attract said armature, and an adjustable stop adapted to vary the limiting position of said armature with respect to said magnet.

6. In a device of the class described, means for holding a contact arm, the same comprising a pivoted catch-lever having means for engaging said arm when in the on position, an electromagnet having a core bored out at one end, and an armature mounted on said-lever and moving coaxially With said core and of a shape adapted to enter the end of said core without touching it.

7. In a device of the class described, means for holding a contact arm, the same comprising a pivoted catch-lever having means for engaging said arm when in the on position, an eleetromagnet having a core bored out at one end, an armature mounted on said lever and moving ooaxially with said core whereby said armature enters the end of but does not touch said core, and an adjustable abutment-screw mounted on said lever and adapted to vary the limiting position of said armature with respect to said magnet.

8. In a device of the class described, the combination of a movable contact-arm having means for restoring it to the off position when released, and means for holding said arm in the on position compris ing a pin on said arm, a pivoted catch-lever, an armature carried by said catch-lever, a magnet adapted to attract and hold said armature, a finger extending from said lever in a position to engage said pin, the end of said finger being oblique to the direction of the movement of said arm and finger, means for limiting the movement of said catch-lever in the direction away from said magnet, means for causing said finger to clear said pin when said arm is moved toward said lever, and means carried by said lever for causing said finger to engage said pin when it is in position for such engagement.

In witness whereof I have hereunto set my hand in presence of two witnesses.

WM. H. GAULKE. Witnesses:

HENRY G. PAGELSDORF, FRANK KRAEMER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

